Fuel economy of an automobile is an important characteristic. A higher fuel economy rating may make a vehicle more attractive to potential buyers and may help an automotive manufacturer meet fuel economy standards imposed by local governments. For traditional gasoline or diesel vehicles, one method of reducing fuel consumption is the use of a micro-hybrid or start-stop powertrain system that selectively turns its engine off during portions of a drive cycle to conserve fuel. As an example, a controller of a start-stop vehicle can turn the engine off while the vehicle is stopped rather than allow the engine to idle. And, the controller can then restart the engine when a driver steps on the accelerator pedal.